I have a 94 Galant GS 4G64 DOHC, my battery died the other day, I got it jumped, and took the alternator in and tested it. If failed, I replaced the battery and the alternator, since the battery was kinda old. Now it runs fine, but when you shut it off, the battery drains. I have some sort of electrical problem and I have no idea where its coming from.

I have good voltage when the car is running both at the battery and from the alternator, but when you shut it off and put a voltmeter on the terminals, the voltage drops. It killed a new battery in about 5.5 hours.

Any help would be appreciated, I'm good with electronics, I just need a place to start looking since I'm new to these cars.

Thanks

Jeff

Okies Jeff , one thing i see happen is that when tightening the power supply wire in the alternator its sumtimes over tightened to where the whole bolt and lead that enters the alternator on the sinc turns a bit , thus causing a small open to ground. Sure it charges fine while running but teh small open to ground that has been created causes a drain on the battery. Here is a test , disconnect teh battery , and then remove the power lead at the alternator and tape it up. Then reconnect the battery terminal and let it sit and check to see if the car turns over or is drained in 6 hours. If so yu will kno for sure that the alternator is creating the power drainage due to an open to ground in continuity. If this is not the case , inspect the smaller charge leads and the connector that goes to the alternator. See if they are broken or damaged. If so , the alternator will be putting out a base charge of 12.5 volts or a little less ,which will merely keep teh electronics running and the car but not enough to recharge teh battery for power lost frum the initial start up process that has drained it.

I have had some trouble with the Electricals on My 96 Galant. I found mine to be a bad alternator even after putting a new one on. In fact I dont recommend Auto Zone alternators. anyways If your Diodes are bad in the alternator it will cause current to backflow and drain your battery. I had my alternator checked by auto zone and it still passed their so called test. I changed it anyway and all my problems are fixed. no more drained battery. So if you did not have the problem before putting on the alternator and have it now I would look closely at that.

I put a amp meter in between the pos cable and the battery to see how much drain and what was going on, it was sitting about 3 amps. I unplugged all the fuses, one by one to see if the drain or went down but it didn't the ones I couldn't do, were the 2 that are screwed in. I know one goes to the alternator so I unscrewed the alternator power cable and my amps dropped to .1 so I think the alternator or something there has a short in it that is causing it to ground out. i don't have any wiring diagrams unless the power cable to the alternator runs the power to the rest of car I don't know. I did all the internal fuses as well with no change.

I just don't see why the alternator would have a 3 amp drain when its just sitting there with nothing taking any power.

Ok just ran my own lil test, had to jump start it, its running, the volts at idle were about 12.8 and over a 15-20 min period they went to 12.2 slowly dropping, this is at idle, with nothing on in the interior. I unhooked the alt as previous mentioned and am going to check the batt voltage in about an hour. It was at 12.2 so we'll see.

Where did you get your new alternator from? I know if you have bad diodes in your alternator it will allow juice from the battery to back feed through the alternator and it will drain your battery. The diodes work like check valves so the power will only run one way.

I got an autozone one because I'm poor and it was 20$ cheaper than the others. I'm gonna take it out and bring it back to them tomorrow, With out it hooked up, my battery hasn't lost a volt over the last 4 hours, as opposed to losing voltage while running.

They also mentioned something that my car has a 75 or a 90 amp alt. I didn't have the extra 40 on me for the 90 amp, so I got the 75 amp.

My car has all the extras but at idle with nothing going you would think it should keep up.

Hello!
I had this problem and I replaced the battery clamps and the problem was solved! I was losing voltage with my car off! I hope this helps as I paid lots of money in labor for the gusy to figure this out! Never had a problem since though!